If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

I'm assuming you have soft spots anyway, so I suggest you drill a hole and take a measurement.......they may have done things differently in 82 then 83. I would not be surprised if you find it to be a bit under 3/4", but not a standard thickness. If this is the case you will just need to purchase the next size below what you have and pad your joists a bit. Just FYI, it's not necessary to to use marine plywood for the repair as they didn't use it originally. Just non treated exterior glue plywood will do the job just fine.

I repaired a chunk of my roof this summer, and you're likely going to run into the same problem I did: Plywood these days is thinner than in the 'old days'. So, if you had 5/8" plywood before (which you probably do), todays 5/8 is 19/32, and 3/4 is 23/32. So 3/4" is still too thick, and 5/8" isn't thick enough. I ended up shimming my patch to bring it level. And I also found out, plywood swells up over the years. I could've ALMOST gotten away with using 3/4", but not quite...